Growth hormone boosts fluid not muscle

Fluid retention, not increased muscle mass, is what you can expect if you take human growth hormone to cheat at sport, a new study shows. So why are drug cheats taking it? (Image: iStockphoto)(Source: iStockphoto)

"My final words would be any one thinking of taking growth hormone should really think very carefully about it," says Nelson.

She says that as well as causing fluid retention, high levels of hGH taken long term can lead to cardiovascular problems and diabetes.

Sports physician Dr Peter Larkins says he hopes the findings are supported by future studies but for now he does not think they will stop the cheats.

"It's unlikely that people are going to be deterred because one study says we don't think [hGH] helps all that much," says Larkins, a medical consultant to the Australian Institute of Sport.

He says people are influenced by powerful anecdotal evidence from the gym, body building and weightlifting worlds that taking five to 10 times the normal levels of hGH makes you leaner and boosts muscle.

The body shape achieved when fluid is retained is quite different to what people are reportedly seeing, says Larkins.

He says he also finds it hard to believe that fluid retention is the main effect of growth hormone given its normally function in the body is to boost protein synthesis.

Larkins would like to see the study repeated using conditions that are closer to those in the field.

But Nelson says there are ethical restrictions on using higher doses and elite athletes.

"We had to be very careful that we didn't have anyone in the study who would be subject to drug testing, or in a situation where taking these drugs was banned," she says.

One interesting finding from the double-blinded study is that there was a very strong placebo effect.

"Half of those who were on placebo actually thought they were taking active treatment," says Nelson.

"In men 80% of the placebo group thought they were on active treatment."